Happened to venture outside this afternoon (in the sunshine ) and heard this high-pitched whistle coming from ? Well..somewhere. My hearing is shot but managed to locate it coming from the log store. Gut feel told me what it was but I wasted time searching.

It's the Clarke portable car-starting-thingummy-jig....haven't charged it for months and months. It's in the same TUIT list as fire-up-the-generator/empty the petrol from the lawn mover/run dry the hedge trimer/strimmer/4000 other things to do before winter.

Zero on the meter. Nada. Zilch. Surprisingly managed to find the charging gizmo and plugged it in. Charging light came on briefly then went out.

Bob, you'd be proud of me...I sussed out instantly what was amiss...so flat the initial current was tripping something internally (charger/gizmo/whatever). So I kept flashing the charging plug in/out/in/out until there was enough charge to coax the circuitry into letting me plug it in fulltime.

Question.....because I let it run so flat, have I nadgered up the plates ? Guess proof of the pudding would be trying to use it...but then I need it to work !

Good strategy for getting it to charge but sadly very poor maintenance strategy for the device in the first place.

I'm assuming this is one of fairly bulky, heavy devices based on sealed lead acid batteries rather than the more modern LiPo based ones?

SLA batteries really do like to be charged at least every few months at constant voltage. 2.35v per cell. Their normal failure condition is to go high internal resistance. The fact that your charger seemed to be being overloaded could be quite encouraging as it would need a low internal resistance to draw enough current to trip the charger.Assuming that the charger will now complete the process, it should drop back to a lower maintenance charge voltage of about 2.25v per cell. I would then gently discharge it - usually these things have a torch built in - to around 1.9v per cell and then re-charge fully before asking it to give its all by starting a vehicle engine.

I have less experience with LiPo but do know their energy density is very very high but in return they do have to be treated carefully with max charge rates and minimum discharge voltage strictly adhered to. Usually they have sophisticated electronics inside to manage this as evidenced by power tools cutting off dead when the battery needs charging.

I will bow to the more experienced around here but is it really necessary to drain petrol from a lawnmower over winter?

I have only owned one ( a Honda) for 11 and a bit years and have never drained the tank over winter. I cut about 1200 m2 once a week from about march to October.

cheers

Andy

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Andyp wrote:I will bow to the more experienced around here but is it really necessary to drain petrol from a lawnmower over winter?

I have only owned one ( a Honda) for 11 and a bit years and have never drained the tank over winter. I cut about 1200 m2 once a week from about march to October.

If it's a Honda and a four-stroke then I'd probably not bother because Honda engines are bloody good. It's not so much draining the tank as running the carb dry AFAIK. Much more imprtant with two-stroke though.

I don't run the carb dry either. I have drained the oil and replaced once, cleaned the plug once and occasionally use the petrol oil mix. Not good news to Bob's ears.

Always starts on 1st or 2nd pull, even the kids can usually start it.

BTW when I need spares for it I go to LINGS Honda, excellent service and way cheaper than locally available here.

cheers

Andy

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DaveL wrote:....Can you measure the voltage of the battery, as Bob suggested? You may find that if you cycle the battery it might recover with a few cycles, but the battery will never be 100%.

How many cells are there ?

Now lets think about this. We are miles away and you have the thing in front of you

Bob

Um...the SLA is sealed inside the case. If you're telling me the cells should be charged at 2.35v or 2.25v per cell then what ? Six cells ? Roughly 12v. Not sure the charger is putting out that much TBH...will measure later. Off and on-load.

I'd assumed a few screws would reveal all. Highly likely to be 6 cells 13.6 ish on charge rapidly falling to 12.6 off charge and slowly reducing to 12 as it discharges. Cease discharge at say 11 v then recharge and repeat Bob

9fingers wrote:I'd assumed a few screws would reveal all. Highly likely to be 6 cells 13.6 ish on charge rapidly falling to 12.6 off charge and slowly reducing to 12 as it discharges. Cease discharge at say 11 v then recharge and repeat Bob

Thanks Bob...will report back. I'm guessing that the output croc clips will be at charger voltage when that's connected. Gives an easy monitoring point. Can't think that there would be anything complicated between charger input socket and the SLA. It is a Clarke after all